<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>棋盘</title>
    <style>
      .board {
        width: 499px;
        height: 499px;
        border: 3px solid #654321;
        border-radius: 5px;
        background-color: #deb887;
        background-image: linear-gradient(to bottom, transparent 49px, #6d4b29 49px), linear-gradient(to right, transparent 49px, #6d4b29 49px);
        background-size: auto 50px, 50px auto;
      }
    </style>
  </head>
  <body>
    <div class="board grid"></div>
  </body>
</html>
